1. Field of the Invention
The present invention relates to a projection display device and a temperature control method thereof.
2. Description of the Related Art
A head-up display (HUD) device for a car in which a windshield of a car or a combiner arranged near the front of the windshield is used as a screen, and projection light is projected onto the screen so that an image is displayed is known (see, for example, JP2014-153578A, JP1998-133177A (JP-H10-133177A), and JP2004-189112A). According to this HUD, a user can view an image that is displayed on a windshield or the like by the projection light projected from the HUD, which is superimposed on a scenery ahead of the own vehicle that is on the back side of the windshield or the like.
The HUD described in JP2014-153578A is configured to dissipate heat from a digital micromirror device (DMD) serving as a light modulation element to the outside by exposing the DMD to outside pores in which outside air are taken. According to this configuration, since the DMD can be cooled without using a fan or the like that cools the DMD, operation sound of the HUD can be reduced.
In the HUD described in JP1998-133177A (JP-H10-133177A), a stable operation can be realized by warming a backlight of a liquid crystal display device serving as a light modulation element under a low temperature environment.
The HUD described in JP2004-189112A has a configuration in which a heat exhaust path is provided between an air conditioning duct for taking air from the interior of a car into an air conditioning device and a light source unit, and an openable and closable shutter is provided in a connection portion between the heat exhaust path and the air conditioning duct.
When the light source unit is started up, the light source unit is cooled by opening the shutter, and the light source unit can be prevented from failing due to heat.